Spring cushioning device for clustered cylinder lifts

ABSTRACT

Spring cushioning devices are provided in each cylinder of a clustered cylinder lift, each device including a single coil-type compression spring operable to cushion its associated cylinder during both extension and retraction thereof.

United States Patent Inventor Frank H. Field 133 East Virginia Blvd., Jamestown, N.Y. 14701 Appl. No 49,401

Filed June 24, 1970 Patented Jan. 11, 1972 Continuation-in-part of application Ser. No. 853,854, Aug. 28, 1969. This application June 24, 1970, Ser. No. 49,401

SPRING CUSHIONING DEVICE FOR CLUSTERED CYLINDER LIFTS 1 1 Claims, 8 Drawing Figs.

U.S. Cl... 92/85 Int. Cl F0lb 11/02 Field of Search 92/84, 85;

[5 6] References Cited UNITED STATES PATENTS 3,382,772 5/1968 Kampert et a1. 92/84 3,072,105 H1963 Johnson 92/84 X 2,692,584 10/1954 Armington 92/168 X 849,506 4/1907 Shadall 92/84 X 3,242,826 3/1966 Smith 92/84 X 3,438,306 4/1969 Kazmarek 92/84 X 3,361,036 l/l968 Harvey 92/171 Primary Examiner Edgar W. Geoghegan Assistant ExaminerLeslie .I. Payne Attorney- Bean & Bean ABSTRACT: Spring cushioning devices are provided in each cylinder of a clustered cylinder lift, each device including a single coil-type compression spring operable to cushion its associated cylinder during both extension and retraction thereof.

mimsumnm 3J633j466 SHEET 1 [IF 3 INVENTOR. FRA NK H. F/ELD A T TORNEYS PATENTED JAN 1 I872 sum 2 UF 3 INVENTOR FRANK H. FIELD A TTORNEYS SPRING CUSHIONING DEVICE FOR CLUSTERED CYLINDER LIFTS CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my copending application Ser. No. 853,854, filed Aug. 28, I969.

BACKGROUND OF THE INVENTION In my copending application Ser. No. 853,854, filed Aug. 28, 1969, there is disclosed a spring cushioning device adapted for use with elevator clustered cylinder lifts in order to prevent jolting and/or sharp accelerations of an elevator car.

The spring cushioning device of my above-mentioned copending application includes a pair of sleevelike members adapted to alternately engage abutrnents disposed adjacent opposite ends of a piston enclosing cylinder casing, a compression spring disposed intermediate the members in a direction axially of the piston and means to slidably mount the members on an end of the piston received with the cylinder casing. The member-mounting means permits movement of an engaged member relative to the piston, while maintaining the other nonengaged member stationary with respect thereto, so as to effect compression of the spring and resultant resilient cushioning of the piston.

More specifically, the members are disposed radially inwardly and outwardly of the piston, and the means for mounting the members includes a pin, which is arranged transversely within the piston to be slidably received within an elongated slot provided in the radially innermost member.

SUMMARY OF THE INVENTION The present invention is directed to an improvement in the spring cushioning device disclosed by my above-mentioned copending application.

In accordance with the present invention, the sleevelike members are of mirror image design and slidably mounted on a reduced diameter, stationary extension of the piston. The members and the jolt-absorbing compression spring arranged therebetween, are retained on the extension by a C-ring received within a groove provided adjacent the free end of the extension.

The present construction results in simplified and thus relative inexpensive fabrication, and reduces to a minimum obstruction to the flow of drive fluid through and/or across the device.

DRAWINGS The nature and mode of the present invention will be more fully described in the following detailed description taken with the accompanying drawings wherein:

FIG. 1 is a perspective view illustrating the positioning of clustered cylinder lifts in association with an elevator car to be lifted thereby;

FIG. 2 is a vertical, sectional view taken through a clustered cylinder lift and showing the individual cylinders retracted so as to position an elevator car adjacent a lower floor level to be serviced thereby;

FIG. 3 is a fragmentary, sectional view of the right-hand, smalldiameter cylinder of FIG. 2, but illustrating operation of its spring cushioning device when such cylinder is moved into its extended position;

FIG. 4 is similar to FIG. 3, but illustrates operation of the spring device when the cylinder is moved into its retracted position; and

FIGS. Sa-Sd are diagrammatic views of a clustered cylinder lift showing relative positioning of the individual cylinders during various portions of elevator car travel.

detailed description In FIG. I, there is shown a conventional elevator lift arrangement, wherein an elevator car is adapted to be elevated within a well 11 between a lower floor level 12 and one or more upper floor levels, not shown, by operation of a pair of clustered cylinder lifts 14, 14" arranged laterally of car 10. Conventional guide rails 15, 15", which are suitably fixed to the walls of well 11, cooperate with suitable car mounted followers, not shown, for the purpose of guiding car 10 during vertical travel thereof.

As shown particularly in the case of lift 14 in FIGS. 1 and 2, each lift includes a large-diameter cylinder 16 and a pair of identically constructed, small-diameter cylinders 17, which have a total effective area corresponding substantially to the effective area of large cylinder 16. Cylinders 16, .17 include, respectively, hollow or tubular pistons 18, 19; and tubular casings 20, 21, which are fixedly interconnected as by weldments 22 or, if preferred, by bolts, not shown. As is conventional, cylinder casings 20, 21 carry adjacent their open ends suitable bearing devices 24, 25 and suitably piston sealing packing gland devices 26, 27, respectively. It will be understood that bearing devices 24, 25, or their ring retainers 28, 29, serve as a first abutment to limit travel of pistons 18, 19 in a cylindrically extended direction. The closed ends 30, 31 of casings 20, 21, or more particularly the sleeve devices 30a, 31a weld affixed to ends 30, 31, serve as a second abutment to limit travel of pistons 18, 19 in a cylinder retracted direction.

Preferably, large cylinder piston 18 is pivotally fixed adjacent its lower end by pivot pin 34 to base-mounting plate 30, whereas small cylinder pistons 19 are pivotally fixed adjacent their upper ends by supporting pivot pin 37 to car-mounting bracket 39 carried by elevator car crossheads 41. By arranging pivot pins 34 and 39 in a right-angular relationship, there is afforded a universal connection, which permits the car and lifts 14, 14' to be self orientating when necessary to compensate for slight tilting movement of guide rails 15, 15" occasioned by settling of the building subsequent to installation of elevator car 10.

Any conventional control equipment, not shown, may be employed to simultaneously supply or exhaust suitably drive fluid, such as oil, through conduits 45 into large cylinder pistons 18 of each of lifts 14, 14" for the purpose of controlling vertical movement of car 10. As best shown in FIG. 2, conduits 47 serve to provide a connection for hydraulic fluid between cylinder 20 and cylinders.21. It will be understood that subsequent to installation of lifts 14, 14", drive fluid is admitted through conduits 45 in order to completely fill cylinders 16, 17; air being fully exhausted from the cylinders through subsequently closable bleed openings 48, 49.

The construction thus far described is identical to that disclosed in my copending application, Ser. No. 853,854, filed Aug. 28, 1969, except for the modification of the second abutment to include sleeve devices 300, 310, which are fixed as by welding to the closed ends and arranged concentrically inwardly of the cylindrical inner. walls of casings 20, 21. Sleeve devices 30a, 31a are preferably provided with transversely extending through openings 30b, 31b to facilitate free flow of drive fluid during operation of the cushioning devices now to be described.

Referring particularly to FIG. 2, it will be understood that in accordance with the present invention, the ends of pistons 18, 19, which are received within cylinder casings 20, 21, are provided with spring cushioning devices 50, 51, respectively. Spring devices 50, 51 are similarly constructed and include, respectively, reduced diameter open-ended sleeves 52, 53, which are fixed as by welding within and extend axially outwardly from the inner ends of pistons 18, 19; first sleeve members 54, 55; second sleeve members 56, 57; and coil-type compression springs 58, 59.

First and second sleeve members 54, 55 and 56, 57, which are shown in FIGS. 2-4 L-shaped cross-sectional construction, include sleeve portions 54a, 55a, and 56a, 57a slidably supported on the cylindrically outer surface of sleeves 52 and 53; and radially extending flange portions 54b, 55b and 56b, 57b arranged for' sliding engagement with the cylindrical inner wall or surface of casings 20 and 21, respectively. Each of flange portions 54b-57b are provided with one or more through slot openings 60 to facilitate free flow of drive fluid across the spring cushioning devices in a direction axially of the pistons.

As will also be apparent from viewing FIGS. 2-4, sleeve portions 54a, 55a and 56a, 57a serve to radially position the respective ends of coil springs 58 and 59 for axial engagement with flange portions 54b, 55b and 56b, 57b.

It will be understood that the sleeve members serve as bearing devices to retain sleeves 52, 53 and thus the inner ends of pistons 18, 19 substantially concentrically of casings 20, 21. To this end the sleeve members are preferably formed of a fine-grade cast iron, whereas sleeves 52, 53 and casings 20, 21 are formed of steel in order to reduce the likelihood of binding or spalling of engaging surfaces during operation.

Economies in fabrication may be realized by dividing a spool-shaped unitary casting to form each pair of first and second sleeve members. Preferably the bearing surfaces are finished prior to dividing the casting in order to reduce by onehalf the finishing operations otherwise necessary if the sleeve members were to be formed separately.

The sleeve members are removably retained on sleeves 52, 53 by stops in the form of steel C or split rings 62, 63, which are snap fitted within annular sleeve surface slots arranged adjacent the free ends of the sleeves. Preferably, C-rings 62, 63 are of circular cross section and are adapted to be partially received within second sleeve member cutouts, which define concave stop surfaces 66, 67 arranged to face both radially inwardly and toward the free end of sleeves 52, 53. By this arrangement, stop surfaces 66, 67 tend to ride up on the radially outer surface of split rings 62, 63 when sleeve members 56, 57 are forced toward the free ends of sleeves 52, 53, thereby exerting a radially inwardly directed force on the split rings tending to retain same seated within their slots. The split rings may, however, be relatively easily removed when desired.

By viewing FIG. 2 it will be understood that during move ment of pistons 18 and 19 between their extended and retracted positions, springs 58 and 59 are normally in a slightly compressed condition, such that they are operable to bias sleeve members 54, 55 and 56, 57 axially apart into their illustrated rest positions.

As will be apparent from viewing FIG. 2, radially extending stop surfaces 74, 75 defined by sleeve members 54, 55 are normally biased into engagement with radially facing extending annular end surfaces 76, 77 of pistons 18, 19, such as to limit or constrain movement of such members relative to the pistons in a direction axially towards bearing devices 24, 25, respectively. Sleeve members 54, 55 are, however, free to slide against the return bias of springs 58, 59, when engaged with bearing devices 24, 25, relative to pistons 18, 19 in a direction axially towards casing end walls 30, 31, as indicated in the case of cylinder 17 in FIG. 3. In a like manner, sleeve members 56, 57 are manually biased into engagement with split rings 62, 63, such as to limit or constrain movement of such members relative to pistons l8, 19 in a direction axially towards casing end walls 30, 31. Sleeve members 56, 57 are however, free to slide against the return bias of springs 58, 59, when engaged with the annular abutment surfaces defined by the free ends of sleeve devices 30a, 31a, relative to the pistons in a direction axially towards the open ends of casings 20, 21 as indicated in the case of casing 17 in FIG. 4.

It will be apparent from viewing FIG. 4, that the abutment surfaces defined by sleeve devices 30a, 31a are arranged radi ally intermediate the outer sleeve members supporting surface of sleeves 52, 53 and the cylindrical inner walls of casings 20, 21, such that sleeve members 56, 57 are engaged thereby, while permitting unobstructed movement of the free ends of sleeves 52, 53, inwardly of the sleeve devices. To prevent jolting, it is of course preferably that sleeve devices are of sufficient axial length to prevent abutment of the free ends of sleeves 52, 53 with end walls 30, 31, when springs 58, 59 are fully compressed.

FIGS. -51! illustrate relative positioning of cylinders 16, 17 during various positions of elevator car travel. In FIG. 5, cylinders 16, 17 are fully retracted so as to position elevator car 10 at its lower floor level. Preferably, in this position, sleeve members 56, 57 are disposed in engagement with cylinder casing end wall mounted sleeve devices 30a, 31a and springs 58, 59 slightly compressed.

When it is desired to elevate the elevator car, drive fluid is introduced through conduit 45 into piston 18 and hence into pistons 19 via openings 30!) and 60, and conduits 47. If desired, sleeves S2, 53 and portions of pistons l8, 19, which do not extend beyond devices 24, 25 when the pistons are extended, may be apertured to facilitate the flow of drive fluid through the casings. Although cylinders 17 have a total effective area equal to that of cylinders 16, the former tend to be extended first, as indicated in FIG. 5b, since cylinder 16 carries the weight of cylinders 17 in addition to that of car 10. Upon movement of cylinders 17 into their fully extended positions, spring devices 51 become effective to prevent jolting engagement of pistons 19 with cylinder casing bearing devices 25. The operation of spring devices 51 during such movement will become apparent from viewing FIG. 3, wherein sleeve member 55 is shown as having been brought into engagement with bearing device 25, such that relative movement between sleeve member 55 and piston 19, and the resultant compression of spring 59, is initiated. Upon compression of spring 59, movement of piston 19 is smoothly arrested and the resultant increase in back pressure within cylinders 17 causes the drive fluid to become effective in extending cylinder 16 into its fully extended position, indicated in FIG. Sc. With cylinders 16, 17 fully extended, car 10 is disposed at the uppermost floor level to be serviced.

When cylinder 16 is moved into its fully extended position,

spring device 50 serves to cushion piston 18 with respect to bearing device 24 in the same manner described above with reference to spring devices 5 1.

It will be understood that when it is desired to lower elevator car 10, as by withdrawing drive fluid through conduit 45 to return the lifts to either of their conditions indicated in FIGS. 5d and 5, the return compression forces stored in springs 58, 59 are effective to initiate retracting movements of the cylinders.

Operation of spring devices 51, upon return of pistons 19 to their retracted positions, is best illustrated in FIG. 4, wherein inner sleeve 57 is shown as having been brought into engagement with cylinder casing and mounted sleeve device 31a. Such engagement effects relative movement between sleeve 57 and piston 19 with the result that spring 59 is compressed.

The operation of spring device 50 when cylinder 16 is moved into fully retracted position is similar to that described for spring devices 51 with reference to FIG. 4.

/ From the foregoing it will be appreciated that I have devised a novel spring cushion device for clustered cylinder lifts, which employs a pair of sleeve members which are alternatively engageable with abutments defining relatively extended and retracted positions of a piston; a sleeve member when engaged being movably relative to the piston and the nonengaged sleeve member for the purpose of compressing a single piston movement cushioning spring.

Whereas only the preferred embodiment of the present invention has been described in detail herein, it will be understood that various changes may be made therein without departing from the spirit of the invention. Exemplary thereof would be to dispense with reduced diameter sleeve extensions fixed to the piston ends and to support the sleeve members directly on the surface of the pistons. However, this construction, as in the case of other alternatives which may likely be devised, would result in reduced efficiency for a given diameter cylinder construction.

I claim:

1. A spring cushioning device for use in a vertically disposed hydraulically operated cylinder employed in a clustered cylinder elevator car lift, said hydraulic cylinder having a piston and a cylinder casing defining first and second piston vertical travel limiting abutments adjacent vertically spaced opposite ends thereof, said piston having an end portion relatively movable axially within said cylinder casing alternately into proximity with said first and second abutments when said piston is moved respectively between extended and retracted positions thereof, said cylinder having a hydraulic fluid inletoutlet means for admitting hydraulic fluid under pressure thereinto for effecting relative vertical movement between said piston and said cylinde. casing to move said piston into said extended position thereof and for withdrawing said fluid therefrom whereby to permit gravity-induced relative vertical movement between said piston and said cylinder casing to move said piston into said retracted position thereof, said spring device including in combination:

first and second members;

means to mount said members on said piston end for movement therewith alternately into respective engagement with said first and second abutments when said piston is moved between said positions, said mounting means defining a radially outwardly facing surface for'slidably supporting said members for movement axially of said piston, said mounting means including means to constrain movement of said first member along said supporting surface relative to said piston in a direction axially towards said first abutment while permitting free-sliding movement of said first member along said supporting surface when engaged with said first abutment relative to said piston in a direction axially towards said second abutment and means to constrain movement of said second member along said supporting surface relative to said piston in a direction axially towards said second abutment while permitting free-sliding movement of said second member along said supporting surface when engaged with said second abutment relative to said piston in a direction axially towards said first abutment;

flow means for facilitating free circulation of hydraulic fluid within said cylinder casing between opposite ends thereof across said members during movement of piston between said positions as aforesaid; and

a single coil spring disposed intermediate said members,

said spring being resiliently compressed upon free-sliding movement of said members along said supporting surface relative to said piston as aforesaid to effect cushioning of said piston end when moved into said positions.

2. A spring cushioning device according to claim 1, wherein said piston is hollow at least adjacent said end thereof, and said mounting means includes a sleeve fixed within and extending axially outwardly from said hollow end of said piston, said sleeve defining said supporting surface.

3. A spring cushioning device according to claim 2, wherein the first said constraining means includes radially extending stop surfaces defined by said first member and said piston end, and the second of said constraining means includes a stop means carried adjacent a free end of said sleeve and a stop surface on said second member engageably with said stop means,

4. A spring cushioning device according to claim 3, wherein said stop means includes a split ring fitted within an annularly extending slot arranged in said supporting surface adjacent said free end of said sleeve, and said second member stop surface when engaged with said split ring exerting a radially inwardly directed force thereon tending to retain said split ring in said slot.

5. A spring cushioning device according to claim 4, wherein said split ring is of circular cross section and said second member stop surface is concave facing radially inwardly and toward said free end of said sleeve.

6. A spring cushioning device according to claim 1, wherein said members are of generally L-shaped cross-sectional configuration having facing sleeve portions arranged for sliding engagement with said supporting surface and radially extending flange portions arranged for sliding engagement with an inner cylindrical wall of said cylinder casing, and said spring is radially positioned adjacent the respective ends thereof by said sleeve portions of said members in axial engagement with said flange portions of said members, and said flow means are in the form of through openings provided at least one in each of said flange portions.

7. A hydraulic fluid operated cylinder of the type employed in clustered cylinder elevator car lifts, the combination comprising:

a vertically disposed piston;

a vertically disposed cylinder casing;

an inlet-outlet means for admitting hydraulic fluid under pressure into said casing for effecting relative movement between said piston and cylinder casing to move said piston into an extended position thereof and for withdrawing said fluid therefrom whereby to permit gravity-induced relative movement between said piston and cylinder casing to move said piston into a retracted position thereof;

first abutment means arranged adjacent an open end of said casing;

second abutment means in the form of a sleeve device arranged adjacent a closed end of said casing concentrically inwardly of the cylindrical inner wall thereof, said sleeve device having an annularly extending free end surface, said piston having an annularly extending free end surface, said piston having an end portion relatively movable axially within said casing alternately into proximity with said first and second abutments when said piston is moved respectively between said extended and retracted positions thereof; first and second members; means to mount said first and second members on said piston end portion for movement therewith alternately into respective engagement with said first and second abutments when said piston is moved between said positions, said mounting means defining a radially outwardly facing cylindrical surface for slidably supporting said members for movement axially of said piston, said sleeve end surface arranged radially intermediate said supporting surface and said inner cylindrical wall of said casing, said first and second members being of annular configuration and extend radially outwardly from said supporting surface for sliding engagement with said cylindrical casing wall such as to maintain said supporting surface concentric inwardly thereof, and said sleeve device and said members having through openings in directions extending transversely and axially of said piston, respectively, whereby hydraulic fluid introduced into said casing for controlling movement of said piston is permitted to flow freely throughout said casing when said piston is moved into said positions, said mounting means including means to constrain movement of said first member along said supporting surface relative to said piston in a direction axially towards said first abutment while permitting freesliding movement of said first member along said supporting surface when engaged with said first abutment relative to said piston in a direction axially towards said second abutment and means to constrain movement of said second member along said supporting surface relative to said piston in a direction axially towards said second abutment while permitting free-sliding movement of said second member along said supporting surface when engaged with said second abutment relative to said piston in a direction axially towards said first abutment; and a coil spring disposed intermediate said members and 'serving as the sole restraint of free-sliding movement of said members towards one another, said spring means being resiliently compressed upon sliding movement of said members along said supporting surface relative to said piston as aforesaid to effect cushioning of said piston end I end of said piston, said open-ended sleeve defines said supporting surface, a free end of said open-ended sleeve being receivable within said sleeve device when said second member is in engagement with abutment surface, the first said constraining means includes radially extending stop surfaces defined by said first member and said piston end, and the second of said constraining means includes a stop means carried adjacent said free end of said sleeve and a stop surface on said second member engageable with said stop means.

9. A hydraulically operated cylinder according to claim 8, wherein said stop means includes a split ring fitted within an annularly extending slot arranged in said supporting surface adjacent said free end of said open-ended sleeve, and said second member stop surface when engaged with said split ring exerting a radially inwardly directed force thereon tending to retain said split ring in said slot.

10. A clustered cylinder construction for effecting vertical movements of an elevator car relative to a support, which comprises in combination:

three vertically extending substantially parallel hydraulically operated extensible cylinders, each said cylinder having a piston and a cylinder casing defining first and second piston travel limiting abutments adjacent vertically spaced opposite ends thereof, said piston having an end portion relatively movable axially within said cylinder casing alternately into proximity with said first and second abutrnents when said piston is moved respectively between cylinder extended and retracted positions, said cylinder casings being fixed one to another, and being connected in free flow hydraulic fluid communication, the piston associated with said inner cylinder being affixed adjacent a relatively outwardly extending end thereof to one of said support and saidelevator car, the pistons associated with said pair of outer cylinders being affixed adjacent relatively outwardly extending ends thereof to the other of said support and said elevator car, said cylinders being characterized as including as pair of relatively outer cylinders arranged one adjacent opposite sides of a relatively inner cylinder wherein the total effective car-lifting area of said pair of outer cylinders substantially corresponds to the effective car-lifting area of said inner cylinder whereby when hydraulic fluid is admitted to or withdrawn from said cylinders at a constant rate said car tends to move throughout its extent of vertical travel at a substantially constant speed;

means for admitting hydraulic fluid under pressure into said cylinders for drivingly extending same thereby to effect lifting of said car and for withdrawing said fluid to permit gravity-induced retraction of said cylinders thereby to effect lowering of said car, operation of said cylinders being characterized in that one of said inner cylinder and said pair of cylinders tends to be initially driven into said extended position thereof on admission of hydraulic fluid to said cylinders to effect lifting of said car, whereafter upon continued admission of hydraulic fluid to further lift said car the other of said inner cylinder and said pair of cylinders are driven into said extended position thereof, and

spring cushioning devices associated one with each of said cylinders, each said spring cushioning device including first and second members, mounting means to mount said members on said piston end portion for movement therewith alternately into respective engagement with said first and second abutments when said piston is is moved between said positions, flow means and a single coil spring, said mounting means defining a radially outwardly facing surface for slidably supporting said members for movement axially of said piston, said mounting means including means to constrain sliding movement of said first member relative to said piston end portion in a direction axially towards said first abutment while permitting free-sliding movement of said first member when engaged with said first abutment relative to said piston end portion in a direction axially towards said second abutment and means to constrain sliding movement of said second member relative to said piston end portion in a direction axially towards said second abutment while permitting free-sliding movement of said second member when engaged with said second abutment relative to said piston end portion in a direction axially towards said first abutment, at least one of said members having a radially outwardly facing surface arranged in sliding bearing engagement with an inner surface of said cylinder casing for maintaining said piston end portion concentrically within said cylinder casing during extensions and retractions of said cylinder, said flow means facilitatingfree circulation of hydraulic fluid axially within said cylinder casing across said device during said extensions and retractions, and said spring being disposed intermediate said members and serving as the sole restraint of free-sliding movement of said members towards one another, said spring being resiliently compressed upon sliding movement of said members relative to said piston end portion as aforesaid to effect cushioning of said piston end portion when moved into said positions and thereby to gradually arrest movement of said one of said inner cylinder and said pair of cylinders when driven into said extended position thereof and to gradually initiate movement of said other of said inner cylinder and said pair of cylinders upon continued admission of hydraulic fluid as aforesaid, and said spring when compressed as aforesaid tending to initiate movement of .said cylinders towards retracted positions thereof upon withdrawal of hydraulic fluid therefrom.

l l. A cylinder construction according to claim 10, wherein said members are of generally L-shaped cross-sectional configuration having facing sleeve portions arranged, for sliding engagement with said supporting surface and radially extending flange portions arranged for sliding engagement with an inner cylindrical wall of said cylinder casing, and said spring is radially positioned adjacent the respective ends thereof by said sleeve portions of said members in axial engagement with said flange portions of said members, and said flow means are in the form of through openings provided at least one in each of said flange portions. 

1. A spring cushioning device for use in a vertically disposed hydraulically operated cylinder employed in a clustered cylinder elevator car lift, said hydraulic cylinder having a piston and a cylinder casing defining first and second piston vertical travel limiting abutments adjacent vertically spaced opposite ends thereof, said piston having an end portion relatively movable axially within said cylinder casing alternately into proximity with said first and second abutments when said piston is moved respectively between extended and retracted positions thereof, said cylinder having a hydraulic fluid inlet-outlet means for admitting hydraulic fluid under pressure thereinto for effecting relative vertical movement between said piston and said cylinder casing to move said piston into said extended position thereof and for withdrawing said fluid therefrom whereby to permit gravity-induced relative vertical movement between said piston and said cylinder casing to move said piston into said retracted position thereof, said spring device including in combination: first and second members; means to mount said members on said piston end for movement therewith alternately into respective engagement with said first and second abutments when said piston is moved between said positions, said mounting means defining a radially outwardly facing surface for slidably supporting said members for movement axially of said piston, said mounting means including means to constrain movement of said first member along said supporting surface relative to said piston in a direction axially towards said first abutment while permitting free-sliding movement of said first member along said supporting surface when engaged with said first abutment relative to said piston in a direction axially towards said second abutment and means to constrain movement of said second member along said supporting surface relative to said piston in a direction axially towards said second abutment while permitting free-sliding movement of said second member along said supporting surface when engaged with said second abutment relative to said piston in a direction axially towards said first abutment; flow means for facilitating free circulation of hydraulic fluid within said cylinder casing between opposite ends thereof across said members during movement of piston between said positions as aforesaid; and a single coil spring disposed intermediate said members, said spring being resiliently compressed upon free-sliding movement of said members along said supporting surface relative to said piston as aforesaid to effect cushioning of said piston end when moved into said positions.
 2. A spring cushioning device according to claim 1, wherein said piston is hollow at least adjacent said end thereof, and said mounting means includes a sleeve fixed within and extending axially outwardly from said hollow end of said piston, said sleeve defining said supporting surface.
 3. A spring cushioning device according to claim 2, wherein the first said constraining means includes radially extending stop surfaces defined by said first member and said piston end, and the second of said constraining means includes a stop means carried adjacent a free end of said sleeve and a stop surface on said second member engageably with said stop means.
 4. A spring cushioning device according to claim 3, wherein said stop means includes a split ring fitted within an annularly extending slot arranged in said supporting surface adjacent said free end of said sleeve, and said second member stop surface when engaged with said split ring exerting a radially inwardly directed force thereon tending to retain said split ring in said slot.
 5. A spring cushioning device according to claim 4, wherein said split ring is of circular cross section and said second member stop surface is concave facing radially inwardly and toward said free end of said sleeve.
 6. A spring cushioning device according to claim 1, wherein said members are of generally L-shaped cross-sectional configuration having facing sleeve portions arranged for sliding engagement with said supporting surface and radially extending flange portions arranged for sliding engagement with an inner cylindrical wall of said cylinder casing, and said spring is radially positioned adjacent the respective ends thereof by said sleeve portions of said members in axial engagement with said flange portions of said members, and said flow means are in the form of through openings provided at least one in each of said flange portions.
 7. A hydraulic fluid operated cylinder of the type employed in clustered cylinder elevator car lifts, the combination comprising: a vertically disposed piston; a vertically disposed cylinder casing; an inlet-outlet means for admitting hydraulic fluid under pressure into said casing for effecting relative movement between said piston and cylinder casing to move said piston into an extended position thereof and for withdrawing said fluid therefrom whereby to permit gravity-induced relative movement between said piston and cylinder casing to move said piston into a retracted position thereof; first abutment means arranged adjacent an open end of said casing; second abutment means in the form of a sleeve device arranged adjacent a closed end of said casing concentrically inwardly of the cylindrical inner wall thereof, said sleeve device having an annularly extending free end surface, said piston having an annularly extending free end surface, said piston having an end portion relatively movable axially within said casing alternately into proximity with said first and second abutments when said piston is moved respectively between said extended and retracted positions thereof; first and second members; means to mount said first and second members on said piston end portion for movement therewith alternately into respective engagement with said first and second abutments when said piston is moved between said positions, said mounting means defining a radially outwardly facing cylindrical surface for slidably supporting said members for movement axially of said piston, said sleeve end surface arranged radially intermediate said supporting surface and said inner cylindrical wall of said casing, said first and second members being of annular configuration and extend radially outwardly from said supporting surface for sliding engagement with said cylindrical casing wall such as to maintain said supporting surface concentric inwardly thereof, and said sleeve device and said members having through openings in directions extending transversely and axially of said piston, respectively, whereby hydraulic fluid introduced into said casing for controlling movement of said piston is permitted to flow freely throughout said casing when said piston is movEd into said positions, said mounting means including means to constrain movement of said first member along said supporting surface relative to said piston in a direction axially towards said first abutment while permitting free-sliding movement of said first member along said supporting surface when engaged with said first abutment relative to said piston in a direction axially towards said second abutment and means to constrain movement of said second member along said supporting surface relative to said piston in a direction axially towards said second abutment while permitting free-sliding movement of said second member along said supporting surface when engaged with said second abutment relative to said piston in a direction axially towards said first abutment; and a coil spring disposed intermediate said members and serving as the sole restraint of free-sliding movement of said members towards one another, said spring means being resiliently compressed upon sliding movement of said members along said supporting surface relative to said piston as aforesaid to effect cushioning of said piston end when moved into said positions.
 8. A hydraulically operated cylinder according to claim 7, wherein said piston is hollow at least adjacent said end thereof, said mounting means includes an open-ended sleeve fixed within and extending axially outwardly from said hollow end of said piston, said open-ended sleeve defines said supporting surface, a free end of said open-ended sleeve being receivable within said sleeve device when said second member is in engagement with abutment surface, the first said constraining means includes radially extending stop surfaces defined by said first member and said piston end, and the second of said constraining means includes a stop means carried adjacent said free end of said sleeve and a stop surface on said second member engageable with said stop means.
 9. A hydraulically operated cylinder according to claim 8, wherein said stop means includes a split ring fitted within an annularly extending slot arranged in said supporting surface adjacent said free end of said open-ended sleeve, and said second member stop surface when engaged with said split ring exerting a radially inwardly directed force thereon tending to retain said split ring in said slot.
 10. A clustered cylinder construction for effecting vertical movements of an elevator car relative to a support, which comprises in combination: three vertically extending substantially parallel hydraulically operated extensible cylinders, each said cylinder having a piston and a cylinder casing defining first and second piston travel limiting abutments adjacent vertically spaced opposite ends thereof, said piston having an end portion relatively movable axially within said cylinder casing alternately into proximity with said first and second abutments when said piston is moved respectively between cylinder extended and retracted positions, said cylinder casings being fixed one to another, and being connected in free flow hydraulic fluid communication, the piston associated with said inner cylinder being affixed adjacent a relatively outwardly extending end thereof to one of said support and said elevator car, the pistons associated with said pair of outer cylinders being affixed adjacent relatively outwardly extending ends thereof to the other of said support and said elevator car, said cylinders being characterized as including as pair of relatively outer cylinders arranged one adjacent opposite sides of a relatively inner cylinder wherein the total effective car-lifting area of said pair of outer cylinders substantially corresponds to the effective car-lifting area of said inner cylinder whereby when hydraulic fluid is admitted to or withdrawn from said cylinders at a constant rate said car tends to move throughout its extent of vertical travel at a substantially constant speed; means for admitting hydraulic fluid under pressure into said cylinders for drivinGly extending same thereby to effect lifting of said car and for withdrawing said fluid to permit gravity-induced retraction of said cylinders thereby to effect lowering of said car, operation of said cylinders being characterized in that one of said inner cylinder and said pair of cylinders tends to be initially driven into said extended position thereof on admission of hydraulic fluid to said cylinders to effect lifting of said car, whereafter upon continued admission of hydraulic fluid to further lift said car the other of said inner cylinder and said pair of cylinders are driven into said extended position thereof, and spring cushioning devices associated one with each of said cylinders, each said spring cushioning device including first and second members, mounting means to mount said members on said piston end portion for movement therewith alternately into respective engagement with said first and second abutments when said piston is is moved between said positions, flow means and a single coil spring, said mounting means defining a radially outwardly facing surface for slidably supporting said members for movement axially of said piston, said mounting means including means to constrain sliding movement of said first member relative to said piston end portion in a direction axially towards said first abutment while permitting free-sliding movement of said first member when engaged with said first abutment relative to said piston end portion in a direction axially towards said second abutment and means to constrain sliding movement of said second member relative to said piston end portion in a direction axially towards said second abutment while permitting free-sliding movement of said second member when engaged with said second abutment relative to said piston end portion in a direction axially towards said first abutment, at least one of said members having a radially outwardly facing surface arranged in sliding bearing engagement with an inner surface of said cylinder casing for maintaining said piston end portion concentrically within said cylinder casing during extensions and retractions of said cylinder, said flow means facilitating free circulation of hydraulic fluid axially within said cylinder casing across said device during said extensions and retractions, and said spring being disposed intermediate said members and serving as the sole restraint of free-sliding movement of said members towards one another, said spring being resiliently compressed upon sliding movement of said members relative to said piston end portion as aforesaid to effect cushioning of said piston end portion when moved into said positions and thereby to gradually arrest movement of said one of said inner cylinder and said pair of cylinders when driven into said extended position thereof and to gradually initiate movement of said other of said inner cylinder and said pair of cylinders upon continued admission of hydraulic fluid as aforesaid, and said spring when compressed as aforesaid tending to initiate movement of said cylinders towards retracted positions thereof upon withdrawal of hydraulic fluid therefrom.
 11. A cylinder construction according to claim 10, wherein said members are of generally L-shaped cross-sectional configuration having facing sleeve portions arranged for sliding engagement with said supporting surface and radially extending flange portions arranged for sliding engagement with an inner cylindrical wall of said cylinder casing, and said spring is radially positioned adjacent the respective ends thereof by said sleeve portions of said members in axial engagement with said flange portions of said members, and said flow means are in the form of through openings provided at least one in each of said flange portions. 